# A student builds a series circuit containing a battery, a diode and a fixed resistor. The student then reverses the connections to the diode so that it faces the opposite direction. Explain what happens to the current in the circuit when the diode is reversed, and why.

> AQA A-Level Physics (7408) — 3.5.1 Current Electricity · Explain · 5 marks

## Mark scheme (5 marks)

1. When the diode is reversed, the current (in the circuit) decreases to (effectively) zero / no current flows
2. Because the diode only allows current to flow in one (forward) direction
3. In the reverse direction the diode has a very high / very large resistance
4. The greater the resistance, the smaller the current (for a given potential difference)
5. In the forward direction the diode has a low resistance, so current flows freely / before reversal current was able to flow

## Key terms

- [diode](https://www.gradenine.co.uk/glossary/diode)
- [current](https://www.gradenine.co.uk/glossary/current)

## Related

- [Revision notes for AQA A-Level Physics (7408)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/a-student-builds-a-series-circuit-0dcde717) · Published by Druglandscape Ltd.